Tokai made Greco's don't have a serial only a model type in the pickup cavity. Sometimes it also lacks the model type so it's good to know how to identify a Tokai opposed to Cort:
Tokai: square tab routing, Cort: oval tab routing
Tokai: medium tenon, Cort: long square tenon (often with bolt)
Tokai: diagonal wire routing, Cort: straight wire routing

Cort made Grecos also have a different kind of plastic in the inlays, the logo and the diamond in case its a Custom. Further, you can see it on the screws which holds the bridge. Also, the Japanese often have nickel and the Korean regular chrome. All of which can be identified easily if the seller provide decent pictures.